Preferences: Appearance Tab.

Preferences: Appearance tab.

Here you may to select overall program appearance. There are three windows styles:

Carbon (It's selected by default):
Carbon style.

Silver style

Native Windows style. (It depends from installed Windows OS version.)
Native Windows Style

Also you may select the appearance of the crop box. Select dotted:

Dotted crop box.

or solid lines and dimmed or not outside areas.
Solid lines and dimmed margins crop box.

The last option allows you to disable or enable "Click" sound that program plays when it saving file.
Click 2 Crop - (C) 2000-2018 by Boris A. Glazer.